Multiple roller coating apparatus



May 25, 1965 D. c. PRATT MULTIPLE ROLLER COATING APPARATUS 4 Sheets-Sheet 1 Filed Feb. 12, 1962 II 42.5% iii:

INVENTOR.

DONALD C. BQAF CARL G. 55077512 A TTORNE Y May 25, 1965 D. c. PRATT MULTIPLE ROLLER COATING APPARATUS 4 Sheets-Sheet 2 Filed Feb. 12, 1962 INVENTOR.

DONALD C. PIP/177' cAkL a. 551/7752 ATTORNEY May 25, 1965 D. c. PRATT MULTIPLE ROLLER COATING APPARATUS 4 Sheets-Sheet 3 Filed Feb. 12, 1962 CARL G. \SA'UUZR ATTORNEY Filed Feb.

IOI

May 25, 1965 D. C. PRATT MULTIPLE ROLLER COATING APPARATUS 4 Sheets-Sheet 4 INVENTOR.

- DONALD c. P45 177 CARL 6. 5507727? ATTORNEY United States Patent 7 3,185,130 MULTIPLE ROLLER COATING APPARATUS Donald C. Pratt, Iselin, N.J., assignor, by mesue assignments, to M & T Chemicals Inc, New York, N.Y., a corporation of Delaware Filed Feb. 12, 1962, Ser. No. 172,487 Claims. (Cl. 118228) The present invention relates to coating apparatus, more particularly of the type in which solid material is coated with a liquid by means of an applicator roller.

It is among the objects of the present invention to provide a coating apparatus in which a layer of liquid coating material deposited by an applicator roller will be of uniform thickness throughout its area.

Another object of the present invention is the prevention of the accumulation of deposits of coating material on the equipment.

It is also an object of the present invention to insure that both the periphery of the applicator roller and the material to be coated travel at the same speed when in contact with each other.

Still another object of the present invention is the provision of apparatus that will be automatically selfadjusting to variations in the position of the surface to be coated, Without altering the essential operative relationships of the apparatus.

Finally, it is an object of the present invention to provide coating apparatus that will be relatively simple and inexpensive to manufacture, easy to operate, maintain and repair, rugged and durable in use, and easy and reliable to operate so as to produce coatings of uniformly desirable characteristics.

Other objects and advantages of the present invention will become apparent from a consideration of the following description, taken in connection with the accompanying drawing, in which:

FIGURE 1 is a schematic perspective view of coating apparatus according to the present invention, showing the essential operative relationships thereof;

FIGURE 2 is a plan view of one of the many possible types of equipment in which apparatus according to the present invention may be embodied and by which methods according to the present invention may be practiced;

FIGURE 3 is an elevational view of the structure of FIGURE 2; and

FIGURE 4 is a section on line 44 of FIGURE 3 in the region of a coating station.

The essential features of the present invention are most clearly appreciated from a consideration of FIGURE 1; and the invention will be first described broadly in terms of FIGURE 1. The remaining figures, which for the most part merely give details helpful in the practice of the invention in a particular environment, will not be discussed until the essential features and relationships have been brought out in connection with FIGURE 1.

Referring then to FIGURE 1, the invention is shown embodied in connection with a coating station 1 through which passes an endless conveyor 3 having an upper run 5 by which articles 7 are carried through the coating station, and a lower run 9. Lower run 9 engages over and rotatably drives an idler roller 11 which also serves as a belt tensioning roller. Although roller 11 is preferably an idler roller, it may also be a drive roller by which conveyor 3 is driven; but either way, run 9 and roller 11 are in drivable engagement with each other. Roller 11 is mounted on and for rotation with a horizontal shaft 13 which also carries a pick-up roller 15 of the same diameter as roller 11. Roller 15 has its lower portion in a reservoir 17 containing a supply of liquid coating material 19; and a lower portion only of roller 15 is immersed in material 19.

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Pick-up roller 15 has a peripheral portion comprising a first contact surface 21 which is the locus of the revolution of a line about a first axis 23 which is the axis of rotation of roller 11, shaft 13 and roller 15. That line is thus the generatrix of surface 21 and is disposed at a substantial angle to all planes perpendicular to axis 23. Preferably, the generatrix is a straight line parallel to axis 23. Surface 21 is bounded by two parallel circular edges which are the loci of the ends of the generatrix.

An applicator roller 25 applies material 19 to article 7 and is rotatable about a second axis 27. Preferably, axes 23 and 27 are disposed at a substantial angle to each other, e.g., 45. Roller 25 has a peripheral portion comprising a second contact surface 29 which is the locus of revolution of a line about axis 27. As in the case of first contact surface 21, second contact surface 29 is bounded by two concentric edges that are the loci of the ends of the generatrix, which in turn is preferably a straight line and in any event is disposed at a substantial angle to all planes perpendicular to axis 27.

Surface 29 contacts articles to be coated along a first line of contact 31 which lies along the generatrix of surface 29 in one position of the generatrix but is substantially shorter. Line 31 is spaced equal distances from the edges of surface 29. One hundred eighty degrees about surface 29 from line 31, surface 29 contacts surface 21 in a second line of contact 33 that is substantially longer than line 31 and in fact in the preferred embodiment extends full width of surfaces 21 and 29. Thus, it is preferred that surfaces 21 and 29 be of the same width. Line 33 is disposed at a substantial angle to any plane perpendicular either to axis 23 or to axis 27 and is preferably perpendicular to line 31.

In addition to its rotative mounting, applicator roller 25 is supported on and forbodily movement with a shaft 35 along the axis of shaft 35, which is not necessarily coincident with axis 27 and in the preferred embodiment is at an acute angle to axis 27. Line 31 and the axis of shaft 35 are at a substantial angle to each other and are preferably perpendicular to each other. The axis of shaft 35 intersects line of contact 31 and preferably bisects it, at a substantial angle that is preferably A coil compression spring 37 acts between an abutment on shaft 35 and a fixed abutment 39 continuously to urge shaft 35 and with it roller 25 toward the article 7 being coated, the applied coating being shown at 19 at the upper right of FIGURE 1. It is important, however, that the movement of shaft 35 be parallel to line 33. Spring 37 assures the desired contact pressure between roller 25 and articles 7 but it is preferred that articles 7 and rollers 15 and 25 be so positioned relative to each other that only a minimum of movement axially of shaft 35 takes place, thereby to preserve as closely as possible the relationship of contact surfaces 21 and 29 to each other.

Preferably, the assembly of roller 15, reservoir 17, roller 25, shaft 35, spring 37 and abutment 39 is duplicated on the other side of conveyor 3, so that there is a roller 15 at each of shafts 13 with roller 11 midway between, and so that the two shafts 35 are coaxial.

A number of novel and important features of the invention result from the above relationships. In the first place, the present invention assures that the thickness of the coating will be uniform throughout, by taking advantage of the fact that a liquid on a surface bounded by opposite edges tends to draw away from the edges and is therefore thinner at the edges than adjacent the center. In View of this phenomenon, it is important that line 33 :be at a substantial angle to any planes perpendicular either to axis 23 or to axis 27, thereby to assure the presence of edges bounding both of surfaces 21 and 29. By contrast, in the prior art, when there was a pick-up roller and an applicator roller whose axes were disposed at an angle to each other, the line corresponding to line 33 was perpendicular to one such axis. The phenomenon of edge drawback is also utilized in the method step of positioning line 31 equal distances from both edges of surface 29. This assures that only the portion of the coating on surface 29 of most uniform depth, namely, that portion immediately adjacent the center, is applied to article 7. It also assures that the depth of the coating material at one end of line 31 will be equal to the depth at the other end, so that upon application to articles 7 the coating material will squeeze out equally in both directions and a more uniform coating on articles 7 will thereby be obtained.

In the second place, the present invention assures that there will be a minimum of relative motion between the applicator roller and the material to be coated. This desirable result is obtained in several ways. One way is by driving only one of rollers 15 and 25, the other of these two rollers being driven by peripheral contact with the one roller. This assures that there are no separate drive trains to get out of synchronism as would be the case if both of rollers 15 and 25 were power driven, with a resultant tendency toward relative motion between surfaces 21 and 29, which in turn would tend to alter the desired operation of applicator roller 25. Preferably, roller 15 is the power driven roller and roller 25 is the idler roller, thereby to afford roller 25 maximum opportunity to adjust its rotation without smearing against articles 7. Minimum relative motion is also achieved by the drive from lower conveyor run 9 to idler roller 11 to pick-up roller 15 to applicator roller 25 and thence to articles 7, in that 9 and 11 must move with the same tangential speed for they are in peripheral contact, as must also 15 and 25; while 11 and 15 must move with the same peripheral speed for they are of the same diameter; and belt runs and 9 must move with the same speed because they are integral. It therefore follows that surface 29 and article 7 will move at the same speed. Also, in the preferred form in which rollers 15 and 25 are duplicated on the other side of article 7, the surfaces 29 of the opposed rollers will have the same peripheral speed for the reasons just set forth.

In the third place, the assembly is rendered automatically self-adjusting to small variations in the position of the surfaces to be coated, by means of spring 37 urging shaft 35 toward articles 7. This adjusting movement, however, does not interrupt the feeding of roller 25 by roller 15, for the direction of adjustive movement is parallel to line of contact 33 between rollers 15 and 25, Also, the line of thrust of spring 37, which is the axis of shaft 35, is centered relative to line of contact 31 so that there is no tendency of the applicator roller assembly to cant relative to articles 7. Moreover, when there are opposed rollers 25 on opposite sides of the conveyor, the common line of thrust is medial of the workpiece and introduces no tendency to misalign the articles.

In the fourth place, the accumulation of material on surface 29 of applicator roller 25 is prevented by the action of roller 15. Roller 25 applies material only along line 31, so that only a central stripe of material is withdrawn from surface 29. The remaining material would tend to build up on either side of that stripe, until the edges of articles 7 tended to fit into an annular valley in surface 29, with resultant loss of uniformity and quality of the applied coating. But roller 15 in contact with roller 25 along line of contact 33 extending substantially full Width of surface 29 acts as a doctor roller that squeezes off the old material and makes room for fresh material across the full width of surface 29. Thus, the fact that line of contact 33 is longer than line of contact 31 is a useful feature of the invention.

The non-essential structural details of one form of apparatus in which the invention may be embodied are shown in FIGURES 2, 3 and 4.

From a consideration of the foregoing disclosure, it

4 will be obvious that all of the initially cited objects of the present invention have been achieved.

It will also be obvious that the invention may be embodied in a wide variety of specific environments. One such environment is illustrated in FIGURES 2, 3 and 4. Referring then to FIGURES 2, 3 and 4, the invention is shown embodied in a machine for priming the edges of ceramic tile. In addition to endless conveyor 3, the machine includes a pair of endless conveyors 101 and 103 spaced apart lengthwise and disposed above conveyor 3, conveyor 101 being disposed adjacent coating station 1 and conveyor 103 being disposed adjacent a second coating station 105. Conveyors 3, 101 and 103 are reeved about head, tail, drive and idler pulleys 107 which may if desired be notched to register with notches on the inner surface of the endless conveyor belts thereby to avoid slippage. Conveyors 101 and 1133 are provided with rails 109 that are spring urged apart so that they not only take up slack in conveyors 1G1 and 1133 but also urge the lower runs of conveyors 193 downward against articles 7 to grasp the articles between superposed coacting conveyor runs. Conventional motor drive means are provided for driving conveyors 3, 101 and 193 at equal speeds with their coacting runs moving in the same direction.

The articles 7 to be coated, such as ceramic tiles, are fed to the left end of the machine as seen in FIGURES 2 and 3 by means of a feed hopper or other feed means (not shown). They lie one deep, one behind the other, on upper run 5 of conveyor 3, by which they are carried beneath the adjacent end of conveyor 101. There the articles encounter guides 111 that orient the articles so that their edges are all perpendicular or parallel to the lengthwise extent of the conveyors.

Articles 7 are carried along between the coacting runs of conveyors 3 and 101 with their side edges projecting laterally beyond the lateral edges of the conveyor belts, and in this position are carried between a first pair of applicator rollers 25 which are rotatably mounted on shafts 113 that converge downward at angles of about 45 to the horizontal. The generatrix of each surface 29 of rollers 25 is inclined at an angle of about 45 to the axis of the roller, so that surfaces 29 contact pick-up roller surfaces 21 in horizontal lines of contact 33 and contact articles 7 in vertical lines of contact 31. Shafts 113 are in turn carried by shafts 35, which are axially aligned for horizontal sliding movement toward and away from each other in sleeves 115 carried by the machine frame. Springs 37 act against fixed abutments 39, which in this case are the cross pieces of U-shaped frames 117 secured to the main machine frame and extending laterally outward therefrom. Springs 37 also act against adjustment nuts 119 which are rotatable on shafts 35 to alter the force with which springs 37 bear against abutments 39. A screw and nut adjustment at 121 also permits the length of shafts 35 in effect to be adjusted, thereby to position rollers 25 closer to or farther from each other.

As explained before, coating material is supplied to applicator rollers 25 by a pair of pick-up rollers 15 mounted on opposite ends of a common shaft 13 and actuated by the peripheral contact of idler 11 with lower run 9 of conveyor 3. This assembly of roller 11 and shaft 13 and two rollers 15 is unitary, and rollers 11. and 15 do not rotate relative to each other or relative to shaft 13. This unitary assembly is carried in sleeves 123 which in turn are mounted for vertical movement in the machine frame and .are adapted to be urged upward or permitted to assume a lower position by means of adjustment screws 125 carried by the machine frame and bearing against the underside of sleeves 123. The tension in conveyor 3 hearing against roller 11 urges the assembly downward against screws 125. Reservoirs 17 are also carried by the machine frame in this region and may be continuously or intermittently supplied with liquid coating material from a further source (not shown).

Each article 7, with a pair of opposite edges coated and a pair of opposite edges uncoated, passes out from beneath the conveyor 101 and is no longer grasped between conveyors 3 and 101. Instead, it is free to turn on conveyor 3; and in this condition it is contacted on one corner by an orienting pin 127 which turns it 90 about a vertical axis passing through conveyor 3 so that the newly coated edges now extend transversely of the conveyor and the uncoated edges extend generally lengthwise of the conveyor. In this oriented condition, the tile then passes between a second set of guides 111 where it is precisely oriented for a second coating operation in second coating station 105, in which the opposed uncoated edges are coated as in station 1, so that all four edges of the article are coated. Apart from the fact that different edges of article 7 are being coated, coating station 105 operates just as coating station 1.

The articles coated on all four edges may then be delivered to a suitable receptacle or further conveyor (not shown) for removal from the machine.

Although the present invention has been described and illustrated in connection with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit of the invention, as those skilled in this art will readily understand. Such modifications and variations are considered to be within the purview or the scope of the present invention as defined by the appended claims.

What is claimed is:

1. Coating apparatus comprising a reservoir for liquid coating material, a rotatably mounted pick-up roller having a lower portion disposed in the reservoir and having a first contact surface, a rotatably mounted applicator roller having a second contact surface, said first and second contact surfaces having continuous contact with each other along a line, and means mounting the applicator roller for movement relative to the pick-up roller parallel to said line of contact.

2. Coating apparatus as claimed in claim 1, and means continuously yieldably urging the applicator roller in one direction parallel to said line of contact.

3. Coating apparatus comprising an endless power driven conveyor disposed adjacent a coating station to move material to be coated through the coating station, a reservoir for liquid coating material, a rotatably mounted pick-up roller having a lower portion disposed in the reservoir and having a first contact surface, a rotatably mounted applicator roller adjacent the coating station and having a second contact surface, said first and second contact surfaces having continuous contact with each other along a line, a shaft on which the pick-up roller is mounted for rotation with the shaft, and a third roller mounted on the shaft for rotation with the shaft in drivable contact with the conveyor and in unitary assembly with the pickup roller and of substantially the same diameter as said first contact surface whereby the applicator roller has a tangential velocity adjacent the coating station substantially equal to the speed of travel of the conveyor.

4. Coating apparatus as claimed in claim 3, the applicator and pick-up rollers being duplicated on opposite sides of the coating station and said third roller being in unitary assembly with both of the pick-up rollers, Whereby the applicator rollers have tangential velocities substantially equally to each other adjacent the coating station.

5. Coating apparatus comprising a reservoir for liquid coating material, a pick-up roller rotatable about a first axis and having a lower portion disposed in the reservoir and having a first contact surface that is a figure of revolution about said first axis, an applicator roller rotatable about a second axis disposed at a substantial angle to said first axis and having a second contact surface that is figure of revolution about said second axis, said first and second contact surfaces having continuous contact with each other along a line disposed at a substantial angle to all planes perpendicular to either of said first and second axes, and means mounting the applicator roller for bodily movement relative to the pick-up roller parallel to said line of contact.

6. Coating apparatus as claimed in claim 5, said line of contact being disposed at an angle of about 45 to said second axis.

7. Coating apparatus as claimed in claim 5, and means continuously yieldably urging the applicator roller in one direction parallel to said line of contact.

8. Coating apparatus as claimed in claim 7, the lastnamed means acting along a line of thrust that intersects said second contact surface on the side of the applicator roller opposite said line of contact.

9. Coating apparatus comprising an endless powerdriven conveyor disposed adjacent a coating station and having one run of the conveyor movable through the coating station to move material to be coated through the coating station and having a second run spaced from the coating station, a reservoir for liquid coating material, a rotatably mounted pick-up roller having a lower portion disposed in the reservoir and having a first contract surface, a rotatably mounted applicator roller adjacent the coating station and having a second contact surface, said first and second contact surfaces having continuous contact with each other along a line, a shaft on which the pick-up roller is mounted for rotation with the shaft, and a third roller mounted on the shaft for rotation with the shaft in driveable contact with said second run of the conveyor and in unitary assembly with the pick-up roller and substantially the same diameter as said first contact surface whereby the applicator roller has a tangential velocity adjacent the coating station substantially equal to the speed of travel of the conveyor.

10. Coating apparatus as claimed in claim 9, the applicator and pick-up rollers being duplicated on opposite sides of the coating station and said third roller being in unitary assembly with both of the pick-up rollers, whereby the applicator rollers have tangential velocities substantially equal to each other adjacent the coating station.

References Cited by the Examiner UNITED STATES PATENTS 771,662 10/04 Peck 118-252 X 1,912,553 6/33 Wagner 118-223 X 1,986,039 1/35 Ackley 118262 X 2,359,015 9/44 Winkel. 2,360,918 10/44 Wade. 2,371,331 3/45 Irwin et a1. 156-546 X 2,516,280 7/50 Welch. 2,539,988 1/51 Calles et al. 118239 X 2,632,918 3/53 Bergstein 118-223 X 3,001,505 9/61 Novick 118261 X FOREIGN PATENTS 915,664 7/46 France.

RICHARD D. NEVIUS, Primary Examiner. 

5. COATING APPARATUS COMPRISING A RESERVOIR FOR LIQUID COATING MATERIAL, A PICK-UP ROLLER ROTATABLE ABOUT A FIRST AXIS AND HAVING A LOWER PORTION DISPOSED IN THE RESERVOIR AND HAVING A FIRST CONTACT SURFACE THAT IS A FIGURE OF REVOLUTION ABOUT SAID FIRST AXIS, AN APPLICATOR ROLLER ROTATABLE ABOUT A SECOND AXIS DISPOSED AT A SUBSTANTIAL ANGLE TO SAID FIRST AXIS AND HAVING A SECOND CONTACT SURFACE THAT IS FIGURE OF REVOLUTION ABOUT SAID SECOND AXIS, SAID FIRST AND SECOND CONTACT SURFACES HAVING CONTINUOUS CONTACT WITH EACH OTHER ALONG A LINE DISPOSED AT A SUBSTANTIAL ANGLE TO ALL PLANES PERPENDICULAR TO EITHER OF SAID FIRST AND SECOND AXES, AND MEANS MOUNTING THE APPLICATIOR ROLLR FOR BODILY MOVEMENT RELATIVE TO THE PICK-UP ROLLER PARALLEL TO SAID LINE OF CONTACT. 